The present invention relates generally to the field of curing hides from a meat-packing plant prior to their shipment to another facility for tanning into leather. In particular, it relates to improved additives for use in hide-curing raceways employed at meat-packing plants and other hide-curing facilities. Hide processing plants cure fresh hides or re-cure previously cured hides. As used herein, xe2x80x9coperatorxe2x80x9d refers to a meat-packer, hide processor or operator of a similar hide-curing facility.
The profitability of a meat-packing plant is greatly affected by the money that the operator receives from various by-products of the meat-packing operation. Typically, the most profitable by-product is from the sale of hides for the production of leather. Because the tanning operation in which the hide is turned into leather is usually conducted at another facility, it is essential for the operator to preserve the value of the hide by curing the hide before shipment to the tanner. The hide must be as clean and free of bacteria as possible in order to avoid decomposition of the hide in the period between removal from the carcass and the tanning operation. That period may be as short as a few days or as long as a year or more.
Decomposition of a hide occurs through the action of bacteria and enzymes, both of these processes being accelerated by heat and moisture. As used herein, references to the deleterious action of bacteria on hides generally refers to the action of both bacteria and enzymes. On a hot summer day, decomposition can begin within four hours of slaughtering and hide removal. Since uncured hides typically contain approximately two-thirds water by weight, the operator should insure that the cured hides are as saturated with salt as possible. This minimizes possible deterioration and reduces the chances of claims by the tanner for insufficient cure.
Perhaps the most significant goal of hide-curing at the meat-packing plant is to reduce the damage that bacteria and other microorganisms can cause to the hide tissue between the time that the hide is flayed from the carcass and the time that it is tanned into leather. Typically the green hide contains contaminants that were present on the animal when it entered the hide processing facility including fresh and decomposed manure and organic matter, such as blood, that are released from the animal during the initial stages of the slaughtering process. All of these organic materials are ideal nutrients for destructive bacteria. If the growth of bacteria is not halted by the curing process, the hide can decompose into a useless, glue-like mass prior to tanning.
The problem of inhibiting microbial growth involves a number of considerations. Obviously, the existing microbial contaminants should be killed or their growth inhibited chemically. In addition, however, it is extremely important to physically remove from the hide the organic material which is an ideal food source for microbes. As mentioned previously, the organic material includes manure, blood and other organic contaminants released in the slaughtering process as well as a not insignificant amount of fat attached to the hide itself. If both considerations are not addressed, any microbes that survive the treatment can propagate in the remaining organic material before tanning is commenced.
The problem of hide-curing has been known for many years. One of the earliest forms of hide-curing was simply to dry the hide in the sun or by artificial means and to physically clean the surface. Although this method was somewhat successful in preventing decomposition of the hide, it was very difficult to re-wet the hide to produce useable leather.
At the present time, meat-packing plants in the United States typically treat green hides in a series of processing steps. These processes are generally described, for example, in U.S. Pat. No. 5,435,808, which is assigned to the assignee of the present invention and is incorporated by reference herein. As described therein, a typical plant may initially treat the hide by cooling it and removing flesh. The preliminary procedures may vary from plant to plant. However, treatment of the hide with a brine is an essential step common to hide-curing processes at meat-packing plants in the United States.
The brine curing is typically conducted in a xe2x80x9craceway.xe2x80x9d Regardless of whether the hide has been fleshed or not, the hide sent to the raceway still contains a layer of fat and organic material, as well as bacteria. The purpose of the hide-curing raceway is to physically remove the remaining fat and organic material and to chemically kill or inhibit the growth of bacteria so that the cured hide will not decompose.
A typical hide raceway is an oval shaped structure filled with brine. These structures are large, containing tens of thousands of gallons of brine and hundreds of hides. Paddle wheels placed on each side of the raceway circulate the hides in the brine to maximize contact between the hides and the brine and the removal of contaminants. The brine is a saturated aqueous solution of salt, usually sodium chloride. Treatment is normally affected for 12 to 72 hours, although the most typical time is about 16 hours.
The brine is an excellent inhibitor of bacterial growth, but does not necessarily kill the bacteria. During the curing it is important to have the hide absorb as much salt as possible to inhibit the future growth of bacteria during storage and shipment. Typically, the hide processor monitors the amount of salt absorbed by the hides by measuring the diminution of the salt remaining in the brine with a salometer. When the salt is absorbed, it replaces a significant portion of the water in the hides and saturates the remainder. As much as two gallons of water are released from each hide. Excess brine is permitted to overflow. The operator of the curing raceway must monitor the salinity of the brine carefully to ensure that the brine remains saturated. If the brine does not remain saturated, the hides will not be saturated with salt and may decompose later.
Because of the foregoing qualities and the fact that it is relatively inexpensive, sodium chloride is the primary hide-curing agent. Potassium chloride can also be used and, indeed, has certain advantages over sodium chloride. However, potassium chloride is not used extensively because of its price. Other hide preservatives and cure accelerators are sometimes added to the brine, but the principal agent is salt. As used herein, xe2x80x9csaltxe2x80x9d refers to potassium chloride, sodium chloride or mixtures thereof.
The cured hides are removed from the brine and are then treated in a wringer or by other means to reduce moisture for the reasons previously noted. A typical hide will contain approximately 48% water by weight at this stage of processing. The hides are then graded, bundled and palletized for shipment. Sometimes they are salted on the flesh side to prevent decomposition before being bundled and palletized. Although brine curing has been utilized since the 1950""s, the process does have certain deficiencies. Among other things, the chemicals used in hide-curing are not environmentally friendly. Increasing environmental concerns significantly limit the disposal of the salt-containing brine. In addition, many of the materials that are added to the hide raceway to improve curing present similar considerations. Some of these materials are expensive, disposal is restricted because of their toxicity, and they are not biodegradable.
Efforts have been made to clean and recycle the brine to minimize the quantity of material to be disposed. Typically, this is done by filtering out some of the solids and then concentrating the remainder by forcing off the excess water in a dehydrator. Unfortunately, organic matter that is recycled back into the raceways acts as food for bacteria. Generally speaking, organic levels in brine exceeding 1% by weight can create high bacteria counts. The halophilic organisms that create the discolorations on the flesh side of the hide during storage are called xe2x80x9cred heat.xe2x80x9d The red heat organisms require high salt concentrations to survive, and thrive in warm, dark, moist environments. If the salt slurry from the dehydrator is added back into the raceway while still hot, the temperature of the raceway will rise, thus favoring red heat growth. Warm brine may help cures in the winter, but in summer it causes red heat to flourish. With the use of dehydrators, red heat has been observed developing on hides in only two weeks time; previously it would have taken weeks or even months for the red discoloration to appear. If the hides develop xe2x80x9cred heatxe2x80x9d or are otherwise improperly cured, the tanner may file a claim against the operator for diminished value or may reject the hides entirely resulting in loss of revenue to the meat-packer.
It is an object of the invention to provide an economical hide-curing additive that prevents the growth of bacteria in the hide raceway and on the hides, is environmentally safe, and is biodegradable.
These and other objects and advantages of the present invention can be achieved utilizing the processes and compositions described herein.
It has now been found that the addition of a solution containing one or more essential oils with antimicrobial properties provides an improved hide-curing additive. In particular, it has been found that the addition of a solution containing one or more non-ionic surfactants, at least one essential oil with antimicrobial properties in a solvent a base provides an improved hide-curing additive.
In general, the composition should contain:
The ingredients may be added pre-mixed to or can be added individually to the hide-curing raceway.
The hide-curing additives of the present invention meet the foregoing objects. They are environmentally safe. A number of the ingredients are approved by the U.S. Agriculture Department for incidental contact with food. They are biodegradable. Pine oil, camphor and other essential oils have microbicidal properties which kill or inhibit the growth of bacteria in the raceway and on the hides. The surfactants in the additive improve the absorption of salt in the hides further enhancing the curing effect of the brine. Other advantages are described herein.
It has now been found that the addition of a solution containing one or more essential oils with antimicrobial properties provides an improved hide-curing additive. In particular, it has been found that the addition of a solution containing one or more non-ionic surfactants, at least one essential oil with antimicrobial properties in a solvent base provides an improved hide-curing additive.
In general, the composition should contain:
In a particularly preferred embodiment, the hide-curing additive contains:
These ingredients may be added pre-mixed to the hide raceway or can be added individually.
Although the preferred embodiment uses a combination of pine oil and camphor as the essential oils, other essential oils having antimicrobial properties may be used. These include, but are not limited to, orange, citronella, d-limonene, dipentene or eugenol. As essential oils, pine oil and camphor are particularly useful for hide-curing and preservation due to their anti-microbial properties and ability to deodorize. These essential oils provide a characteristic but pleasant odor that mask some of the more unpleasant odors in the hide house.
The essential oil chosen may be used alone or in combination with other essential oils having antimicrobial properties. The compositions of the present invention can also include or be used in conjunction with other compatible biocides.
A solvent for the essential oils is used as a carrier. The principal criteria in selecting the solvent is it""s ability to deliver the essential oils and surfactant to the hide, rather than dispersing it throughout the aqueous brine in the hide raceway. Accordingly, a non-aqueous solvent is used. Preferred carriers include aliphatic solvents, such as hydrogenated petroleum distillates, particularly those of a food grade quality. Aliphatic solvents with flash points xe2x89xa7140 deg. F. are preferred. Petroleum ether is another solvent that could be used in accordance with this invention. Other suitable solvents include pentane, hexane, cyclohexane, petroleum naptha, heptane, VMandP naptha, 90 solvent (i.e., an aliphatic solvent with a flash point of 90 deg. F.), mineral spirits, odorless mineral spirits, low odor base solvent, 140 solvent (i.e., an aliphatic solvent with a flash point of 140 deg. F.) and mineral seal oil. Gasoline and diesel fuel, also aliphatic solvents, are undesirable for commercial purposes because of their high vapor pressure, low flash point and water pollution concerns. All of the foregoing non-aqueous solvents form a dispersion containing the essential oils and surfactant on the surface of the brine in the hide raceway, therefore, bringing those ingredients into preferential contact with the hides. In contrast, an aqueous solvent would disperse the additive throughout the brine, significantly adding to the cost of application.
LPA-210 is a preferred solvent. It is a paraffinic/napthenic solvent made by Vista Chemical of Houston, Tex. It is approved by the U.S. Food and Drug Administration for use in applications where it may have incidental contact with food. It has a flash point of more than 201xc2x0 F., which means that it is xe2x80x9cnoncombustiblexe2x80x9d under Department of Transportation regulations. Also, it is biodegradable.
The non-ionic surfactants are used both to assist in dispersing the essential oil into the raceway brine and to aid in absorption of the salt by the hides. When the ingredients are pre-mixed, the surfactant also assists in coupling the essential oils into the formula. The surfactants should be used in amounts which accomplish these purposes. Suitable surfactants include primary and secondary alcohol ethoxylates, nonylphenol ethoxylates, and block polymer surfactants. Particularly preferred are T-Det N4 and T-Det N-9.5 which are sold under those trade marks by Harcros Chemicals, Inc., Kansas City, Kans. These products are nonylphenoxypolyethoxyethanols having moles of ethoxylation of 4 and 9.5, respectively. Nonylphenoxypolyethoxyethanols having other moles of ethoxylation can be used alone or in combination.
It is possible to overwet a hide. If a disproportionate amount of lower molecular weight surfactant is used, the formulation will not disperse uniformly into the brine. This will result in uneven cures and may cause other problems to the hide. Use of excess surfactant or wetting agent can result in absorption by the hide of undesirable materials from the brine, such as, manure and other organic material. In general, wetting agents and surfactants should be used in amounts that do not result in absorption of materials through the exterior side of the hide. This amount may vary depending on the surfactant, wetting agent and essential oil that is used.
Generally, the hide-curing additive of the present invention is added to the raceway after the hides have been introduced and curing has begun. An advantage of the present invention is that the preferred composition is highly concentrated, i.e., it is necessary to use only about one-third (i.e., ⅓) gallon per 100 fleshed hides or one-half (i.e., xc2xd) gallon per 100 unfleshed hides.
The process of the present invention has a number of advantages. First, it is much safer to use than existing additives that are flammable and are difficult to dispose of. The ingredients of the present hide-curing additives do not have an Environmental Protection Agency, xe2x80x9cRQ,xe2x80x9d i.e., reportable quantity, which mandates reporting to government authorities in the event that a spill or release occurs in excess of the designated quantity. Many of the ingredients may be used in food processing plants, an indication of their safety; the compositions are biodegradable. In addition, the invention provides a more efficient way to cure hides in that salt absorption by the hides is maximized. This increases the storage life of the hides, minimizes the possibility of xe2x80x9cred heat,xe2x80x9d and ensures acceptability of the hides by tanners. The hide-curing additives of the present invention deodorize and provide a clean, medicinal smell. Hides cured using the additives of the present invention have a supple xe2x80x9chandle.xe2x80x9d Fold marks are removed from previously cured and bundled hides.
Modifications may be made in the compositions of the present invention without significantly affecting the process results. For example, non-ionic fluoro surfactants, such as FC 431 manufactured by 3M Specialty Chemicals Division of 3M, St. Paul, Minn., may be used to obtain additional wetting. Biocides such as chlorinated or quaternary ammonium disinfectants which are compatible with the other ingredients may also be used.